Apparatus for melt spinning filaments which will coalesce



June 23 1959 w. L. suToR ,277

APPARATUS FOR MELT SPINNING FILAMENTS WHICH WILL COALESCE Filed June 24, 1953 0 0 0 0 o o o o o O00 O00 o 0 OOO 0 0 oooo 2w H z IN VENTOR Walter L. 511101" ATTORNEY l... I V 3 Example IV A spinneret plate containing 90 holes, consisting of 18 of the 5-holed patterned arrangement of Figure 11, is drilled. Six of these patterned arrangements are protruded 0.003 inch. Other dimensions of the plate are as described in Example I. The plate is locked in equipment as described in Example I. A yarn is spun employing the melt and technique of Example I. The filaments from the protruded and the non-protruded patterned arrangements are collected as separate yarns. Examination of the yarn from the 6 protruded patterned arrangements disclosed no split filaments. An average of 9 filaments of the 12-filament yarn showed incompletely coalesced strands.

The nature and viscosity of the polymer to be extruded, the particular patterned arrangement employed and the size and spacing of the individual holes within each patterned arrangement are variables, the combined effect of which determines optimum operating conditions and optimum protrusion at each patterned arrangement. In general, it isdesirable to extrude at as low a temperature as possible to avoid unnecessary plastic flow in the extruded mass. The individual holes within each patterned arrangement must be maintained small to present a structure having a relatively large surface area to crosssection which is easily quenched. These individual holes must be close enough together Within each patterned arrangement that coalescence of the individual strands within each arrangement occurs. A protrusion of patterned arrangement of as low as 0.001 inch has been found beneficial. It is preferred to protrude within the limits of about 0.002 to about 0.005 inches. A protrusion of about 0.0035 permits a wide range of adaptability to other variables. Protrusions above about 0.0065 inch frequently will not give the effect desired.

In general, it may be stated that optimum temperature for the melt-spinning of any particular polymer will be slightly lower when practicising the present invention than is usually employed in the conventional melt-spinning of the same polymer. A pack temperature of from about 255 C. to about 290 C. is recommended for the spinning of polyethylene terephthalate having a relative viscosity of from 25 to 35 when following the teachings of the present invention. Polyhexamethylene adipamide, having a relative viscosity within the range of 25 to 45, is best spun at a pack temperature of from 245 C. to 270 C. when proceeding in accordance with the present invention.

Rapid quenching of the extruded filament assists in the arrest of its plastic flow. It is promoted by maintaining 'the diameter of the extruded individual strand as low as practicable in order to assist heat transfer after extrusion. In general, a hole diameter of from about 0.004 to about 0.030 inch has been found suitable for the meltspinning of polyesters and polyamides. A relatively highvelocity, low-temperature air stream is also beneficial in obtaining this result. Cocurrent or countercurrent flow at the spinneret face may be advantageously employed. In any of these techniques, care must be taken to avoid fouling the extruded filaments, one with the other. Beside quenching in air, quenching in any inert cooling fluid may be employed.

The thickness of the spinneret plate is not critical.

trusion' orifices.

It should be maintained as thin as practicable in order to avoid temperature changes of the polymer melt between its polymer melt surface and the extrusion surface. Furthermore, a thick plate introduces friction losses. The matter of strength of the plate must be considered and this will depend not only on its thickness but on its material of construction. For a chromium steel plate (such as illustrated in United States Patent No. 2,341,555) a plate thickness of from about 0.2 to about 0.4 inch is sufficient. It is possible to decrease the thickness at each extrusion point by countersinking on the polymer melt face over each patterned arrangement. In this manner, it is possible to have as low an effective thickness at the point of extrusion as about 0.01 inch when using a plate of the metal described above. The thickness of the web at the extrusion face of the spinneret plate should be kept as low as practical. The maximum permissible thickness will be primarily related to the size of the ex- However, the nature of the extruded polymer will also affect it to a certain degree. Where the orifice diameter is between the limits of about 0.004 to about 0.030 inch and the polymer is a member of the group consisting of polyesters and polyamides, the web thickness at the extrusion face is advantageously maintained at about 0.002 inches and is preferably maintained between the limits of about 0.001 and about 0.003 inch.

This invention is applicable broadly in the production of all types of fiber-forming synthetic linear polymers which are capable of being melt spun. Illustrative of polyamides and copolyamides which can be spun employing the apparatus of this invention are those described in any of the United States Patents Nos. 2,071,250,

2,252,557 and 2,374,137. Examples of polyesters and 2,071,250, 2,071,251, 2,465,150 and 2,465,319.

-Many other modifications within the scope of the disclosed invention, without a departure from the inventive concept, will be apparent to those skilled in the art.

- What is claimed is:

1. A spinneret plate for melt-spinning which comprises a solid plate having at least one protrusion which extends gradually outward from the spinneret face for a distance of from about 0.001 to about 0.0065 inches, each protrusion having a group of holes in which the web thicknesses between adjacent holes in the group are less than about 0.003 inch, and with each group of the said holes having on the polymer melt face of the said plate a .inch.

References Cited in the file of this patent UNITED STATES PATENTS 2,001,000 Taylor et al. May 14, 1935 2,148,221 Echneider Feb. 21, 1939 2,149,425 Draernann Mar. 7, 1939 2,252,689 Bradshaw Aug. 19, 1941 Webb May 22, 1951 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 2,891,277 June 23, 1959 Walter L Sutor It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should readas corrected below.

Column 1, line 20, for 'means" read meant column 2, line 27, for "No. 2,266,268.." read No, 2,266,368, column 3, line 39, for

practicising" read practicing column 4, line 61, in References I Cited list, for "Echneider" read Schneider I Signed and sealed this let da5 of December 1959.,

(SEAL) Attest:

KARL HQ AXLINE Attesting Ofiicer ROBERT C. WATSON Commissioner of Patents 

1. A SPINNERET PLATE FOR MELT-SPINNING WHICH COMPRISES A SOLID PLATE HAVING AT LEAST ONE PROTRUSION WHICH EXTENDS GRADUALLY OUTWARDLY FROM THE SPINNERET FACE FOR A DISTANCE OF FROM ABOUT 0.0001 TO ABOUT 0.0065 INCHES, EACH PROTRUSION HAVING A GROUP OF HOLES IN WHICH THE WEB THICKNESS BETWEEN ADJACENT HOLES IN THE GROUP ARE LESS THAN ABOUT 0.003 INCH, AND WITH EACH GROUP OF THE SAID HOLES HAVING ON THE POLYMER MELT FACE OF THE SAID PLATE A REGION WHICH IS COUNTER-SUNK TO A DEPTH LESS THAN THE THICKNESS OF THE SAID PLATE. 